Method and Network Node for Facilitating Synchronization in Network

1. A method for facilitating synchronization in a network, the method comprising, at a network node: receiving synchronization signals from one or more neighboring network nodes; determining whether the one or more neighboring network nodes have reached a synchronized state based on the synchronization signals; determining whether a difference between a current synchronization value of the network node and an average of synchronization values of the one or more neighboring network nodes exceeds a threshold, the synchronization values being estimated based on the synchronization signals; and obtaining an updated synchronization value of the network node based on the synchronization values of the one or more neighboring network nodes, regardless of the current synchronization value, in response to a determination that the one or more neighboring network nodes have reached the synchronized state and the difference exceeds the threshold.

2. The method of claim 1 , further comprising: refraining from transmitting any synchronization signal in response to the determination that the one or more neighboring network nodes have reached the synchronized state and the difference exceeds the threshold.

3. The method of claim 1 , wherein each synchronization value comprises a time-domain synchronization value and a frequency-domain synchronization value, and wherein it is determined that the one or more neighboring network nodes have reached the synchronized state when the one or more neighboring network nodes have reached the synchronized state in both time domain and frequency domain, and wherein the threshold comprises a time-domain threshold and a frequency-domain threshold and it is determined that the difference exceeds the threshold when a difference between the current time-domain synchronization value of the network node and an average of the time-domain synchronization values of the one or more neighboring network nodes exceeds the time-domain threshold, a difference between the current frequency-domain synchronization value of the network node and an average of the frequency-domain synchronization values of the one or more neighboring network nodes exceeds the frequency-domain threshold, or both.

4. A method for facilitating synchronization in a network, the method comprising, at a network node: receiving synchronization signals from one or more neighboring network nodes; determining whether the one or more neighboring network nodes have reached a synchronized state based on the synchronization signals; determining whether a difference between a current synchronization value of the network node and an average of synchronization values of the one or more neighboring network nodes exceeds a threshold, the synchronization values being estimated based on the synchronization signals; setting a transmission period at which the network node transmits synchronization signals according to whether in response to a determination that the one or more neighboring network nodes has reached synchronized state, and/or the difference between the synchronization values exceed the threshold.

5. The method of claim 4 , further comprising: obtaining an updated synchronization value of the network node based on the synchronization values of the one or more neighboring network nodes, regardless of the current synchronization value, in response to determinations that the one or more neighboring network nodes have reached the synchronized state and the difference exceeds the threshold.

6. The method of claim 4 , further comprising: indicating the transmission period, or a change thereof, to the one or more neighboring network nodes.

7. The method of claim 6 , wherein the transmission period or change thereof is indicated by: broadcasting a message indicating the transmission period, or change thereof, to the one or more neighboring network nodes; including in each transmitted synchronization signal an information element indicating the transmission period or change thereof, or transmitting a synchronization signal in a predefined format associated with the transmission period.

8. The method of claim 4 , wherein setting the transmission period comprises: setting the transmission period to a first period when it is determined that the one or more neighboring network nodes have not reached the synchronized state; and setting the transmission period to a second period longer than the first period when it is determined that the one or more neighboring network nodes have reached the synchronized state and that the difference does not exceed the threshold.

9. The method of claim 4 , wherein setting the transmission period comprises: setting the transmission period at which the network node transmits synchronization signals to a second period when it is determined that the difference does not exceed the threshold; and setting the transmission period to a first period shorter than the second period when it is determined that the difference exceeds the threshold and that the one or more neighboring network nodes have not reached the synchronized state.

10. The method of claim 4 , wherein it is determined whether the one or more neighboring network nodes have reached the synchronized state by: determining a period at which each of the one or more neighboring network nodes transmits the synchronization signals; determining a deviation of each of the synchronization values of the one or more neighboring network nodes from the average; or determining a variation of each of the synchronization values of the one or more neighboring network nodes over time.

11. The method of claim 4 , wherein each synchronization value comprises a time-domain synchronization value or a frequency-domain synchronization value.

12. The method of claim 4 , wherein each synchronization value comprises a time-domain synchronization value and a frequency-domain synchronization value, and wherein it is determined that the one or more neighboring network nodes have reached the synchronized state when the one or more neighboring network nodes have reached the synchronized state in both time domain and frequency domain, and wherein the threshold comprises a time-domain threshold and a frequency-domain threshold and it is determined that the difference exceeds the threshold when a difference between the current time-domain synchronization value of the network node and an average of the time-domain synchronization values of the one or more neighboring network nodes exceeds the time-domain threshold, a difference between the current frequency-domain synchronization value of the network node and an average of the frequency-domain synchronization values of the one or more neighboring network nodes exceeds the frequency-domain threshold, or both.

13. A network node for facilitating synchronization in a network comprises a transceiver, a processor and a memory, wherein the memory contains instructions executable by the processor whereby the network node is operative to: receive synchronization signals from one or more neighboring network nodes; determine whether the one or more neighboring network nodes have reached a synchronized state based on the synchronization signals; determine whether a difference between a current synchronization value of the network node and an average of synchronization values of the one or more neighboring network nodes exceeds a threshold, the synchronization values being estimated based on the synchronization signals; set a transmission period at which the network node transmits synchronization signals according to whether in response to a determination that the one or more neighboring network nodes has reached synchronized state, and/or the difference between the synchronization values exceed the threshold.

14. The network node of claim 13 , wherein the instructions are such that the network node is further operative to: obtain an updated synchronization value of the network node based on the synchronization values of the one or more neighboring network nodes, regardless of the current synchronization value, in response to a determination that the one or more neighboring network nodes have reached the synchronized state and the difference exceeds the threshold.

15. The network node of claim 13 , wherein the instructions are such that the network node is further operative to: indicate the transmission period, or change thereof, to the one or more neighboring network nodes.

16. The network node of claim 15 , wherein the instructions are such that the network node is further operative to: broadcast a message indicating the transmission period, or change thereof, to the one or more neighboring network nodes; include in each transmitted synchronization signal an information element indicating the transmission period, or change thereof, or transmit a synchronization signal in a predefined format associated with the transmission period.

17. The network node of claim 13 , wherein the instructions are such that the network node is further operative to: set the transmission period to a first period when it is determined that the one or more neighboring network nodes have not reached the synchronized state; and set the transmission period to a second period longer than the first period when it is determined that the one or more neighboring network nodes have reached the synchronized state and that the difference does not exceed the threshold.

18. The network node of claim 13 , wherein the instructions are such that the network node is further operative to: set the transmission period at which the network node transmits synchronization signals to a second period when it is determined that the difference does not exceed the threshold; and set the transmission period to a first period shorter than the second period when it is determined that the difference exceeds the threshold and that the one or more neighboring network nodes have not reached the synchronized state.

19. The network node of claim 13 , wherein the instructions are such that the network node is further operative to: determine a period at which each of the one or more neighboring network nodes transmits the synchronization signals; determine a deviation of each of the synchronization values of the one or more neighboring network nodes from the average; or determine a variation of each of the synchronization values of the one or more neighboring network nodes over time.

20. The network node of claim 13 , wherein each synchronization value comprises a time-domain synchronization value or a frequency-domain synchronization value.